1. Field of the Invention
The present invention relates to an optical apparatus having a digital image forming means, and more particularly to an optical apparatus arranged in such a manner that an optical means changes an aspect ratio (which is hereinafter defined as height-to-width ratio) of image information on a moving picture or a still picture photographed, by compressing or expanding either one of the vertical and horizontal lengths, then the image information with the aspect ratio thus modified is recorded in a recording medium such as a CCD having a pixel array arranged in a non-square lattice pattern with the small aspect ratio, and, upon sampling of square lattice from the image information formed in the recording medium, a distortion of the aspect ratio is corrected to output correct image information.
2. Related Background Art
Cost-performance ratios have been increasing these years with wide spread use of computer devices. This is realized in that relatively cheap devices are able to perform various image processing operations, which have been handled heretofore only by expensive large-scale devices, and demands to take a digitized image into a computer or the like have been increasing in various technical fields. Sampling is necessary for digitizing analog image information. A two-dimensional sampling technique needs to be employed for sampling of image information as being two-dimensional data. Normally, square lattices are frequently used for sampling because of easiness of handling of memory.
Presently, commonly used image pickup means for converting the image information into an electric signal is the CCD in which a plurality of light-receiving elements are arranged in a two-dimensional pattern. According to the television standards, the CCD is formed from a plurality of light-receiving elements arranged in a non-square lattice, for example approximately at a ratio of height:width=1.05:1. Therefore, if signal processing are performed while taking image information pieces from the respective light-receiving elements in the image pickup means with the plurality of light-receiving elements arranged in such a non-square lattice into a square lattice, the image would contract vertically to provide image information with a distorted aspect ratio.
A technique to prevent it is a method of resampling to achieve the ratio of height:width=1:1 upon performing the image processing. However, because a change of the sampling ratio of 1.05:1 to 1:1 is very small, moire is likely to appear in the high-frequency region, resulting in forming a poor image. There is a method using a low-pass filter in order to prevent the moire, but this method has a problem of difficult setting of the low-pass filter.
Further, the method by image processing requires separate digital circuits for the horizontal and vertical directions in an image processing circuit, thus having a problem that the circuit arrangement tends to become complex. These problems could be overcome if an image pickup means in which light-receiving elements are arranged in a square lattice pattern were used. However, most image pickup means are those having the pixel array determined according to the standards, as described above. Further, the image pickup means presently commonly and readily available include a small total number of pixels, and cannot fully meet the demands to achieve high definition.